Senior Software Engineer, Infrastructure at Retell AI | San Francisco

Join the Revolution at Retell AIRetell AI is pioneering the future of call centers through innovative voice AI, driven by first principles thinking.In just 18 months since our inception, we have empowered thousands of businesses with our AI voice agents, transforming how sales, support, and logistics calls are managed—previously requiring extensive human teams. Supported by prestigious investors such as Y Combinator and Alt Capital, we've rapidly scaled from $5M ARR to an impressive $36M ARR with a compact yet dynamic team of 20.Our ambition for 2026 is to create a revolutionary customer experience platform, where entire contact centers are powered by AI. Moving beyond basic automation, we aim to develop intelligent AI “workers” that serve as frontline agents, QA analysts, and managers, continuously enhancing customer interactions without the need for constant human oversight.As we expand, we are seeking passionate engineers who are eager to solve challenging technical problems, act swiftly, and make a significant impact in one of the fastest-growing voice AI startups. Let’s shape the future together.

Join Our Innovative Team at Retell AIRetell AI is at the forefront of revolutionizing the call center industry through advanced voice AI technology. In just 18 months since our inception, we have empowered thousands of businesses to optimize their sales, support, and logistics calls, which previously relied on large teams of human agents. Supported by prominent investors including Y Combinator and Alt Capital, we've achieved remarkable growth, scaling from $5 million to $36 million in annual recurring revenue (ARR) while expanding our talented team to 20 members.Our ambitious vision for 2026 is to develop a state-of-the-art customer experience platform, transforming entire contact centers with AI. Unlike traditional automation that requires ongoing human oversight, we are building intelligent AI "workers" capable of functioning as frontline agents, quality assurance analysts, and managers, constantly enhancing customer interactions.If you are a passionate innovator eager to solve complex technical challenges and make a tangible impact at one of the fastest-growing voice AI startups, we invite you to join us in shaping the future.Ranked among the top 50 AI applications by a16z: a16z List4th on Brex's Fast-Growing Software Vendors of 2025: Brex BenchmarkFeatured as a leading startup on: Leanaileaderboard

About Retell AIAt Retell AI, we are pioneering the future of call centers through innovative voice AI technology. Our cutting-edge solutions are transforming how companies engage with customers.In just 18 months since our inception, we've empowered thousands of businesses with our AI voice agents that efficiently manage sales, support, and logistics calls, significantly reducing the need for large teams of human agents. Supported by industry-leading investors including Y Combinator and Alt Capital, we've grown our annual recurring revenue from $5M to an impressive $36M while expanding our team from 5 to 20 talented individuals since 2025.Our ambitious vision for 2026 is to develop a state-of-the-art customer experience platform where entire contact centers are driven by AI. Unlike basic automation requiring constant human oversight, we’re engineering intelligent AI “workers” capable of serving as frontline agents, quality assurance analysts, and managerial roles, all while optimizing customer interactions continuously.We are rapidly expanding and seeking driven builders who thrive on solving complex technical challenges, act decisively, and wish to make a tangible impact in one of the fastest-growing voice AI startups.Join us in shaping the future!Recognized as a top 50 AI application in the a16z list: https://tinyurl.com/5853dt2xRanked #4 in Brex's Fast-Growing Software Vendors of 2025: https://www.brex.com/journal/brex-benchmark-december-2025Featured among the top startups on: https://leanaileaderboard.com/

Join Retell AIAt Retell AI, we leverage first principles to revolutionize the call center experience through innovative voice AI technology.In just 18 months since our launch, our AI voice agents have been adopted by thousands of companies to manage sales, support, and logistics calls, significantly reducing the need for large teams of human agents. Supported by Y Combinator, Alt Capital, and other notable investors, we've achieved impressive growth, scaling from $5M to $36M ARR with a dedicated team of 20.Looking ahead to 2026, we aim to create a comprehensive AI-powered Customer Experience (CX) platform that transforms entire contact centers. Instead of simple automation requiring ongoing human oversight, we are developing intelligent AI "workers" that serve as frontline agents, QA analysts, and managers — perpetually executing, monitoring, and enhancing customer interactions.We're experiencing rapid growth and are on the lookout for passionate innovators eager to tackle complex technical challenges, accelerate progress, and make a significant impact at one of the leading voice AI startups.Let’s build the future together.Ranked in the top 50 AI applications by a16z: https://tinyurl.com/5853dt2x#4 on Brex's Fast-Growing Software Vendors list for 2025: https://www.brex.com/journal/brex-benchmark-december-2025One of the top startups on: https://leanaileaderboard.com/

Join Retell AI as a Senior Machine Learning EngineerRetell AI is at the forefront of revolutionizing the call center industry using groundbreaking voice AI technology. Within just 18 months of our inception, we have empowered thousands of businesses with our AI voice agents capable of managing sales, support, and logistics calls that traditionally required extensive human teams.Supported by renowned investors, including Y Combinator and Alt Capital, our journey has seen us scale from $5M to an impressive $36M ARR with a dedicated team of 20. Our ambition for 2026 is to develop a state-of-the-art customer experience platform, transforming entire contact centers with AI. We are building intelligent AI “workers” that will serve as frontline agents, quality assurance analysts, and managers—constantly executing, monitoring, and enhancing customer interactions.We are rapidly expanding and seeking passionate innovators eager to solve complex technical challenges and make a tangible impact in one of the fastest-growing voice AI startups. Together, let's shape the future of customer interactions.

About Retell AIRetell AI is pioneering the future of customer service by leveraging first principles to transform the call center experience through advanced voice AI technology.In just 18 months since our inception, our innovative AI voice agents have been utilized by thousands of companies to efficiently manage sales, support, and logistics calls, significantly reducing the need for large teams of human agents. With the backing of esteemed investors such as Y Combinator and Alt Capital, we have achieved an impressive $36 million ARR, growing from $5 million at the beginning of 2025 with a dedicated team of 20 professionals.Our ambitious vision for 2026 is to develop a state-of-the-art CX platform powered entirely by AI. We aim to create intelligent AI 'workers' that will function as frontline agents, QA analysts, and managers, capable of autonomously executing, monitoring, and enhancing customer interactions.We are rapidly expanding and seeking passionate innovators eager to solve challenging technical problems, work swiftly, and make a tangible impact at one of the fastest-growing voice AI startups. Join us in shaping the future.Recognized as a top 50 AI app in a16z's list: https://tinyurl.com/5853dt2xRanked #4 on Brex's Fast-Growing Software Vendors of 2025: https://www.brex.com/journal/brex-benchmark-december-2025Listed among the top-ranking startups at: https://leanaileaderboard.com/About the RoleAs the Support Engineering Lead at Retell, you will be responsible for overseeing the technical support operations of our sophisticated voice AI platform. This hands-on leadership position involves directly troubleshooting complex customer challenges, developing AI agents and automations, and leading an expanding team of support engineers.You will work at the intersection of engineering, customer relations, and product development, ensuring unparalleled reliability, swift issue resolution, and scalable support systems as Retell continues its growth trajectory.This position is perfect for individuals who thrive on resolving intricate technical issues under pressure, engaging with clients directly, and constructing systems and teams from the ground up.

About Retell AI Retell AI builds voice AI technology for call centers, helping thousands of companies handle sales, support, and logistics calls with AI voice agents. Since launching 18 months ago, the company has grown annual recurring revenue from $5M to $50M, backed by investors including Y Combinator and Alt Capital. Our Mission By 2026, Retell AI aims to deliver a customer experience platform powered entirely by AI. The vision goes beyond basic automation: intelligent agents will take on roles as frontline workers, quality assurance analysts, and managers, improving customer interactions while reducing the need for ongoing human involvement. Recognition Ranked among the top 50 AI applications by a16z (a16z List) #4 on Brex's Fast-Growing Software Vendors of 2025 (Brex Benchmark) High placement on the Leana AI Leaderboard Working at Retell AI The team is expanding quickly and welcomes those who want to solve tough problems and help shape the future of voice AI. Retell AI is based in the San Francisco Bay Area and continues to grow as one of the industry's fastest-moving startups.

Join Us at Retell AIRetell AI is revolutionizing the call center industry by leveraging innovative voice AI technology based on first principles.In just 18 months since our inception, we have attracted thousands of companies that rely on Retell's AI voice agents to efficiently manage sales, support, and logistics calls, previously handled by large teams of human agents. Supported by renowned investors such as Y Combinator and Alt Capital, we have rapidly grown from $5M to $36M in Annual Recurring Revenue (ARR) with a dedicated team of 20.Looking ahead to 2026, our ambition is to establish a state-of-the-art customer experience platform entirely powered by AI. We aim to create intelligent AI “workers” capable of serving as frontline agents, quality assurance analysts, and managers, continuously optimizing customer interactions without the need for constant human oversight.We are on an exciting growth trajectory and are seeking driven individuals who are eager to solve complex technical challenges, accelerate progress, and make a significant impact at one of the fastest-growing voice AI startups.Let’s innovate the future together!Ranked as a top 50 AI app by a16z: https://tinyurl.com/5853dt2x#4 on Brex's Fast-Growing Software Vendors of 2025: https://www.brex.com/journal/brex-benchmark-december-2025One of the top startups on: https://leanaileaderboard.com/

Join Retell AI as a Senior Full Stack Software EngineerAt Retell AI, we are revolutionizing the call center industry with innovative voice AI technology. Our cutting-edge solutions are designed to improve communication efficiency, allowing businesses to automate sales, support, and logistics calls that once required large teams of human agents. In just 18 months, we have experienced remarkable growth, achieving $36M in annual recurring revenue with a dedicated team of 20, up from $5M at the beginning of 2025.Our goal for 2026 is to create a modern customer experience platform powered entirely by AI. We are not just automating but building intelligent AI agents that can perform the roles of frontline agents, quality assurance analysts, and managers, continuously enhancing customer interactions.We are rapidly expanding and seeking talented individuals who are ready to solve challenging technical problems, work at a fast pace, and make a significant impact in one of the fastest-growing voice AI startups.Let’s shape the future of communication together!

Role overview retell-ai seeks a Senior Software Engineer in the San Francisco Bay Area to focus on Go-To-Market (GTM) projects. This engineer will help shape how new products are created and introduced to customers, directly influencing the company’s approach to launching and scaling offerings. What you will do Collaborate with teams across the organization to translate business needs into software that advances GTM objectives. Develop and improve products to ensure they fit seamlessly into the market. Uphold high standards for code quality and system performance as products grow and change. Collaboration This position works closely with product, business, and engineering partners to deliver solutions that address both technical and market demands.

ABOUT RETELL AIRetell AI is at the forefront of revolutionizing call centers with innovative voice AI technology, utilizing first principles to redefine customer interactions.In just 18 months since our inception, thousands of companies have adopted Retell's AI voice agents to manage sales, support, and logistics calls that previously required extensive human teams. Supported by prestigious investors such as Y Combinator and Alt Capital, we have rapidly scaled to $36M ARR with a lean team of 20, up from $5M at the start of 2025.Our vision for 2026 is to create a modern customer experience (CX) platform where entire contact centers are powered by AI, moving beyond basic automation that relies on constant human intervention to intelligent AI “workers” that operate as frontline agents, quality assurance analysts, and managers, continuously executing, monitoring, and enhancing customer interactions.As we grow, we seek passionate builders eager to tackle challenging technical problems, accelerate progress, and make a genuine impact within one of the fastest-growing voice AI startups.Join us in shaping the future.Ranked among the top 50 AI applications in a16z's list: https://tinyurl.com/5853dt2x#4 on Brex's Fast-Growing Software Vendors of 2025: https://www.brex.com/journal/brex-benchmark-december-2025Also recognized as a top-ranking startup on: https://leanaileaderboard.com/ABOUT THE ROLEAs a Senior Software Engineer - Support Automations at Retell, you will take charge of the technical support for our advanced, agentic voice AI platform. This hands-on leadership role involves personally troubleshooting complex customer issues, developing AI agents and automations, and guiding a growing team of support engineers.You will work at the intersection of engineering, customer relations, and product development, ensuring exceptional reliability, swift resolutions, and scalable support as Retell expands.This position is perfect for someone who thrives on solving intricate technical challenges in high-pressure environments, engages directly with customers, and enjoys building systems and teams from the ground up.

About UsAt Hayden AI, we are dedicated to leveraging the capabilities of computer vision to revolutionize how transit systems and government agencies tackle pressing real-world issues.Our cutting-edge mobile perception system enhances bus lane enforcement, transportation optimization, and much more, empowering our clients to speed up transit, improve street safety, and work towards a sustainable future.About the RoleThe Infrastructure Engineering team plays a vital role in the success of Hayden AI products. We are responsible for the foundational infrastructure that links thousands of deployed devices to our extensive, multi-region cloud services and applications that utilize the data collected from these devices. If you consider yourself a force multiplier, you’ll thrive in our dynamic team!Key Responsibilities:Architect the Service Backbone: Lead the design and continuous improvement of our core services architecture, ensuring a robust, high-availability backbone for all cloud services and engineering teams.Drive Technical Roadmap: Define the long-term technical strategy and architectural vision for our cloud services, aligning with future business expansion and technological advancements.Strategic Decision Making: Lead pivotal architectural decisions, conduct in-depth code reviews, and assess technical trade-offs to maintain a sustainable and scalable service ecosystem.Scale Multi-Region Cloud: Design and oversee globally distributed, multi-region cloud deployments utilizing advanced Infrastructure as Code (IaC) for optimal scalability and performance.Automate Everything: Employ automation and modern orchestration tools to minimize manual tasks, enabling a self-service infrastructure model that allows developers to deploy code swiftly and safely.

Responsibilities:Develop Our Product. Take ownership of software features that enhance our AI platform, empowering private market investors to analyze deals swiftly and accurately. This role requires you to actively engage in coding and delivering essential platform components from the ground up.Ensure Quality and Excellence. Establish and maintain coding standards, architectural guidelines, and review procedures; mentor fellow engineers. Co-cultivate a culture centered on practical, reliable, and test-driven development that swiftly meets business requirements.Scale for Growth. Assist in monitoring and scaling the architecture of our platform and its infrastructure.Collaborate Across Functions. Engage closely with product, security, and go-to-market teams to translate our strategic roadmap into actionable features and deliverables.

At Greptile, we are on a mission to develop intelligent agents that autonomously verify code modifications. Our current focus involves utilizing AI to analyze pull requests on GitHub, effectively identifying bugs and enforcing coding standards. With our technology, we review nearly 1 billion lines of code each month for over 3,000 companies.Challenges We Are Excited To TackleDeveloping agents that can learn coding standards through experience, similar to how new hires adapt.Determining customer-specific preferences for pull request feedback using sample-efficient reinforcement learning to enhance signal-to-noise ratios.Implementing automated deployments of feature branches and leveraging agents to stress-test the application for bug detection.Our Growth TrajectoryServing over 7,000 customers.Successfully raised $30 million from prominent investors including Benchmark, Y Combinator, Paul Graham, and Initialized.Our TeamWe have curated a highly skilled team that has successfully scaled vital functions at leading companies such as Stripe, Google, Figma, and others.Key ResponsibilitiesDesign and implement resilient infrastructure to accommodate Greptile's expanding user base.Collaborate with our largest enterprise clients to facilitate the deployment of Greptile within their environments.Streamline the on-premise deployment process to support smaller clients with minimal hands-on intervention.

ABOUT RETELL AIRetell AI is pioneering the transformation of traditional call centers through innovative voice AI technology.In just 18 months since our inception, thousands of businesses leverage Retell's AI voice agents to efficiently manage sales, support, and logistics calls that previously required extensive human teams. Supported by Y Combinator, Alt Capital, and other esteemed investors, we've experienced rapid growth, increasing our annual recurring revenue (ARR) from $5M to $36M with a dedicated team of 20.Looking ahead to 2026, we aim to develop a comprehensive customer experience (CX) platform, fully powered by AI. Our goal is to go beyond basic automation, creating intelligent AI “workers” that serve as frontline agents, quality assurance analysts, and managers—constantly optimizing and enhancing customer interactions.As we expand, we are seeking enthusiastic builders ready to engage with complex technical challenges, accelerate innovation, and make a significant impact at one of the fastest-growing voice AI startups.Join us in shaping the future!Featured as a top 50 AI app on a16z's list: https://tinyurl.com/5853dt2xRanked #4 on Brex's Fast-Growing Software Vendors of 2025: https://www.brex.com/journal/brex-benchmark-december-2025One of the top startups on: https://leanaileaderboard.com/

About LightfieldLightfield is an innovative AI-driven CRM that seamlessly integrates your email, calendar, and meetings into an organized platform. It captures every interaction and transforms it into actionable insights, tasks, accounts, and follow-ups, ensuring that nothing is overlooked.We are revolutionizing the CRM landscape from the ground up. Rather than imposing rigid structures on teams, Lightfield adapts to how businesses naturally operate, automating processes and highlighting insights that foster growth. We are crafting the CRM platform of our dreams: fast, intelligent, and genuinely beneficial.Supported by esteemed investors like Greylock, Lightspeed, and Coatue, our team has a rich history of building impactful products, including Tome, a generative AI presentation tool embraced by over 25 million users. Our collective experience spans companies such as Llama, Instagram, Facebook Messenger, Pinterest, Google, and Salesforce.About the RoleWe are in search of a skilled, innovative, and adaptable engineer excited to take on the challenge of designing, developing, and scaling the foundational infrastructure and systems that power Lightfield's AI-enhanced CRM.At Lightfield, engineers take full ownership of projects from ideation to execution, collaborating across various functions and pushing the boundaries of what is achievable in applied AI and data systems. You will play a pivotal role in crafting and constructing the data models and infrastructure that support a next-generation CRM, ensuring optimal performance, scalability, and resilience.What You'll DoDevelop and sustain full-stack systems, ensuring reliability, scalability, and robust performance.Architect and enhance the data infrastructure and backend services that drive Lightfield's AI-powered CRM.Design and refine data models to facilitate CRM workflows, customer interactions, and AI-derived insights.Create observability and metrics frameworks to promote seamless operations, proactive issue detection, and ongoing enhancements.Guide colleagues, engage in code reviews, and contribute to shaping the engineering culture and best practices.Play a key role in cultivating a top-tier engineering team through recruitment, mentorship, and knowledge exchange.Who You ArePossess 3+ years of software development experience, with a solid foundation in infrastructure, data modeling, and backend systems.Demonstrate extensive experience in designing scalable, high-performance systems.

fractional-ai is looking for a Senior or Staff Software Engineer to join the San Francisco office. This position centers on building advanced AI solutions with a team that values both technical depth and collaboration. Role overview This role focuses on designing and developing AI-driven systems. The work involves solving technical challenges and contributing to projects that push the boundaries of what AI can achieve. Collaboration with other engineers and stakeholders is a key part of daily responsibilities. Who will thrive Experienced engineers with a strong background in software development Those who enjoy working on complex technical problems Individuals who value teamwork and open communication Location This position is based in the San Francisco office.

About Flow EngineeringAt Flow Engineering, we are pioneering an AI-native requirements platform that empowers cutting-edge engineering teams to collaborate seamlessly with AI agents. Our mission is to facilitate the design, validation, and evolution of complex systems with unmatched speed and precision. Following our successful Series A funding, we are on an exciting trajectory to scale our product from thousands to hundreds of thousands of users, all while upholding the highest standards of reliability and performance.About the RoleWe are seeking a passionate Infrastructure Software Engineer to join our dynamic team. In this role, you will be instrumental in constructing and expanding the core platform that underpins Flow. You will manage services and infrastructure that empower "agentic systems engineers" and product teams to leverage Flow in their daily tasks.You will become a key member of a small, senior team that prioritizes speed, ownership, and solid engineering principles—delivering version 1 products swiftly, learning, and iterating effectively.Your ResponsibilitiesDesign, develop, and maintain backend services and platform primitives that facilitate complex engineering workflows and large-scale collaboration.Enhance Flow’s capacity from thousands to hundreds of thousands of users, focusing on performance, reliability, observability, and security across the entire stack.Take ownership of CI/CD pipelines, testing infrastructure, and internal tools to enable rapid and safe product releases.Collaborate with frontend and AI engineers to establish robust APIs, data models, and integration points that are easy to adapt and evolve.Contribute to architectural decisions and the technical roadmap as our product and customer base expands.Your ProfileA minimum of 3 years of software engineering experience in building and maintaining production systems within a cloud environment (e.g., AWS or GCP).Deep understanding of systems design, distributed systems, and best practices for reliability, observability, and security.Proficiency with containerization and infrastructure-as-code tools (e.g., Docker, Terraform, etc.).Ability to take ownership of projects end-to-end in a fast-paced environment and make pragmatic decisions amidst ambiguity.A collaborative mindset with low ego, eager to work closely with product, design, and customer-facing teams.Our Technology StackUtilization of TypeScript, Node.js, and React for application development, with a strong emphasis on type safety.Employing Postgres and various managed cloud services for data persistence and messaging.

fractional-ai is hiring a Software Engineer to join the team onsite in San Francisco. This role centers on building and improving technology that advances artificial intelligence. Role overview As a Software Engineer, you will work closely with others to develop and support projects that drive the company’s AI initiatives forward. The work involves collaborating with colleagues and contributing technical solutions in a team setting. What you will do Develop software for AI-driven projects Collaborate with team members in the San Francisco office Contribute ideas and technical expertise to ongoing initiatives Requirements Interest in technology and artificial intelligence Ability to work onsite in San Francisco Strong motivation to learn and contribute to team projects

About Our TeamJoin our dynamic Infrastructure organization at OpenAI, where we are actively seeking talented software engineers to bolster our efforts across several high-impact teams. With a variety of focus areas available—including Core Distributed Systems, Databases, Observability, and Cloud Infrastructure—you'll have the opportunity to work on projects that fascinate you. Our teams operate with a high level of autonomy and foster a deeply collaborative environment, all dedicated to enhancing safety, reliability, and operational velocity across the organization.About the RoleAs a Software Engineer focused on Infrastructure Reliability, you will play a pivotal role in scaling and fortifying the infrastructure that supports some of the world’s most widely utilized AI systems. Your work will ensure that our systems maintain high reliability, observability, performance, and security—enabling researchers to iterate rapidly and allowing products like ChatGPT and the OpenAI API to effectively serve millions of users.This hands-on, impactful role is perfect for engineers who enjoy ownership, excel at solving complex technical challenges across the entire stack, and wish to contribute to systems that facilitate cutting-edge research deployed on a global scale. You will significantly influence technical direction, enhance system resilience, and collaborate closely with infrastructure, product, and research teams to transform intricate infrastructure into dependable platforms.Key ResponsibilitiesDesign, construct, and maintain reliable, high-performance systems utilized across engineering.Identify and resolve performance bottlenecks and inefficiencies, ensuring our infrastructure scales appropriately.Investigate and troubleshoot complex issues thoroughly.Enhance automation to minimize manual tasks and improve internal developer tools.Participate in incident response, postmortem analysis, and the development of best practices surrounding system reliability and scalability.Ideal Candidate ProfilePossess a deep understanding of distributed systems principles, with a proven track record in developing and managing scalable, reliable systems.Demonstrate a strong focus on performance and optimization, with the ability to maximize efficiency in complex, globally distributed systems.Have experience managing orchestration systems such as Kubernetes at scale and creating abstractions over cloud platforms.Be comfortable working within Linux environments and possess strong problem-solving skills.